Fuel feed device and fuel pressure regulator

ABSTRACT

Mounted on the upper surface of the cover portion ( 3 ) of a fuel supplying apparatus ( 10 ) to be mounted to an opening portion ( 2   a ) of a fuel tank ( 2 ) is a fuel pressure regulator ( 20 ), which contains a fuel pressure detector portion ( 21 ) constituted by a diaphragm portion ( 21   a ) detecting a pressure of the fuel discharged from a fuel pump ( 4 ) and a current control portion ( 22 ) for analogue-controlling the current flowing through the fuel pump ( 4 ) by a signal from the fuel pressure detector portion ( 21 ), whereby the fuel pump ( 4 ) is set to pump an amount of the fuel corresponding to that required by the injector mounted to the engine, so that the current consumption of the fuel pump ( 4 ) is reduced and the operating noise is lowered.

TECHNICAL FIELD

This invention relates to a furl supplying apparatus mounted within afuel tank of an automobile or the like for supplying fuel under pressureto an injector which injects fuel to an engine.

BACKGROUND ART

FIG. 5 is a sectional side view of the conventional fuel supplyingapparatus disclosed in International Publication No. WO96/23967.

In the figure, a fuel supplying apparatus 1 which comprises as anassembly a cover 3, a fuel pump 4, a fuel filter 5, a pressure regulator6, a discharge pipe 7, an unillustrated fuel level indicator and anunillustrated electrical connector is suspended from an opening 2 a of afuel tank 2 made of a metal or a resin.

The fuel filter 5 comprises a holder member 5 a made of an electricallyconductive resin and a filter element contained therein and is welded toa boundary 8 between the cover 3 in a liquid-tight manner. The holdermember 5 a holds the fuel pump 4 at its central portion and the pressureregulator 6 at the lower end portion. A gasket 9 for the gas-tight sealis interposed between the cover 3 and the fuel tank 2.

In the holder member 5 a of the fuel filter 5, an inlet portion 10 as afuel inlet for the fuel filter 5 is disposed at the upper portion of theinner circumference of the holder member 5 a and is connected to thedischarge pipe 11 of the fuel pump 4 through a seal 10 a. Also, theholder member 5 a of the fuel filter 5 has two fuel outlets, a pipe 12(shown by a dot-and-dash line) constituting the first fuel outletextending axially upwardly from the bottom end of the holder member 5 a.The pipe 12 is connected to the discharge pipe 7 to supply the filteredfuel to the injector. A return path 13 constituting the second fueloutlet is disposed at the lower portion of the holder member 5 a and isconnected to the pressure regulator 6.

14 is a strainer for filtering fuel before it is suctioned into the fuelpump 4 against any foreign matters such as iron powders within the fueltank 2.

The pressure regulator 6 is inserted at its base 6 a into insertionportion 5 c extending downwardly from the bottom of the holder member 5a and is fixed thereto. A diaphragm 6 c is held between the open end ofthe housing 6 a and the housing 6 b, and the diaphragm 6 c supports amovable valve seat 6 e having an discharge hole 6 d.

Within the base 6 a, a stationary valve seat 6 f that co-operates withthe movable valve seat 6 e is fixed. Between the housing 6 b and thediaphragm 6 c, a spring 6 g is received and a exhaust port 6 h fordischarging the fuel from the discharge hole 6 d into the fuel tank 2 isdisposed at the lower portion of the hosing 6 b.

4 a a current supply unit for supplying an electric current to anunillustrated motor of the fuel pump 4 and electrically connected to anunillustrated electrical connector integrally formed with the cover 3.

In the fuel supply apparatus thus constructed 1, when an electriccurrent is supplied to the unillustrated motor of the fuel pump 4 fromthe unillustrated electrical connector through the current supplyportion 4 a, the motor rotates, and the fuel within the fuel tank 2 issuctioned through the strainer 14 and after discharged from thedischarge pipe 11 flows through a passage 15 in the direction of anarrow A to pass through the filter element 5 b to reach to a lower space16 defined under the filter element 5 b.

One part of the fuel is flowed into the pressure regulator 6 and, whenthe fuel pressure becomes higher than the set pressure of the spring 6g, the diaphragm 6 c is moved toward the housing 6 b to open thedischarge hole 6 f of the movable valve seat 6 e so that the fuel withinthe base 6 a is returned through the discharge port 6 h to the fuel tank2 again. The other part of the fuel flows through the pipe 12 in thedirection of an arrow B to be supplied to the injector of a fuelinjection apparatus mounted to an unillustrated engine through thedischarge pipe 7.

In the conventional fuel supplying apparatus, the motor of the fuel pump4 is supplied with a constant continuous electric power so that aconstant amount of fuel is pumped from the fuel tank 2, and the fueldemanded by the injector associated with the engine is supplied throughthe discharge pipe 7 and the excessive amount of fuel is all returned tothe fuel tank 2 from the discharge hole 6 d of the pressure regulator 6through the discharge port 6 h.

The fuel pump 4 is set to pump an amount of the fuel equal to or morethan that required by the engine at the time of the maximum load.However, the fuel amount required by the engine injector during idlingis small, so that most of the pumped fuel is returned to the fuel tank 2through the discharge port 6 h of the pressure regulator 6.

As discussed above, the fuel pump motor is always driven at the fullpower irrespective of the fuel amount required by the injector, so thatthe electric current consumption of the fuel pump 4 is high and the loadto the battery mounted on the vehicle is high. Also, since the motor ofthe fuel pump 4 is operated at a high speed even when the engine noiseis low such as during the idling, the operating noise of the fuel pump 4is high.

This invention has been made to solve the above-discussed problems andhas as its object the provision of a fuel supplying apparatus in whichthe fuel pump is operated to discharge an amount of the fuelcorresponding to the fuel amount required by the injector, whereby thecurrent consumption of the fuel pump is reduced and the operating noiseis lowered.

DISCLOSURE OF INVENTION

The fuel supplying apparatus of the present invention comprises a coverportion installed to an opening portion of a fuel tank and having anoutlet pipe disposed thereon, a fuel pump for pumping fuel within thefuel tank to an injector of an engine through the outlet pipe, a fuelfilter for filtering the fuel discharged from the fuel pump, and a fuelpressure regulator for detecting the pressure of the fuel dischargedfrom the fuel pump and regulating the discharge pressure of the fueldischarged from the pump according to the detected fuel pressure.

The fuel pressure regulator may comprise a fuel pressure detectionportion and a current control portion for controlling the currentflowing through the fuel pump according to a signal from the fuelpressure detection portion.

The fuel pressure regulator may comprise a diaphragm portiondisplaceable in response to the fuel pressure, a compression spring foradjusting the displacement amount of the diaphragm portion and a shaftfor guiding the movement of the diaphragm in a predetermined direction.

The current control portion may be composed of an analogue circuitcomprising a variable resistor of which resistance varies according tothe amount of displacement of the shaft, and a transistor of which basecurrent is controlled according to the variable resistor.

Further, the present invention resides in a fuel pressure regulatingapparatus comprising a suction portion for suctioning fuel, a fuelpressure detection portion for detecting fuel pressure, and a currentcontrol portion for controlling a current flowing through a fuel pumpaccording to a signal from the fuel pressure detection portion.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more readily apparent from thefollowing detailed description of the preferred embodiments of thepresent invention taken in conjunction with the accompanying drawings,in which:

FIG. 1 is a sectional side view of the fuel supplying apparatus of oneembodiment of the present invention;

FIG. 2a and 2 b are enlarged view of the fuel pressure regulator shownin FIG. 1;

FIG. 3 is a connection diagram for a vehicle of the fuel supplyingapparatus of one embodiment of the present invention;

FIG. 4 is an enlarged sectional side view of the fuel pressure regulatorof another embodiment of the present invention; and

FIG. 5 is a sectional side view of a conventional fuel supplyingapparatus.

BEST MODES FOR CARRYING OUT THE INVENTION

FIG. 1 is a sectional side view of the fuel supplying apparatus of oneembodiment of the present invention, in which a fuel supplying apparatus100 which comprises as an assembly a cover 3, a fuel pump 4, a dischargepipe 7, a strainer 14, a fuel pressure regulator 20 and a fuel levelindicator (not shown) is suspended from an opening 2 a of a fuel tank 2made of a metal or a resin.

The fuel filter 5 comprises a holder member 5 a made of an electricallyconductive resin and a filter element contained therein and is welded toa boundary 8 between the cover 3 in a liquid-tight manner. The holdermember 5 a holds a pipe 12 (shown by a dot-and-dash line) which is afuel outlet of the fuel filter 5, the pipe 12 extending axially upwardlyfrom the bottom end.

The pipe 12 is connected to the discharge pipe 7 to supply the filteredfuel to the injector. A fuel pressure regulator 20 is disposed on theupper surface of the cover 3 of the passage (hereinafter referred to asa fuel pipe) for flowing the fuel connected to the injector through thedischarge pipe 7 from the pipe 12 and detects the fuel pressure. 14 is astrainer for filtering fuel before it is suctioned into the fuel pump 4against any foreign matters such as iron powders within the fuel tank 2.

FIG. 2a and 2 b are enlarged side views of the fuel pressure regulatorshown in FIG. 1, and (a) is a sectional side view and (b) is a sectionalview taken along lien II—II of FIG. 2a.

In the figures, the fuel pressure regulator 20 comprises a fuel pressuredetector unit 21, a current control unit 22 and a case 23.

The fuel pressure detector unit 21 comprises a diaphragm portion 21 adisplaceable in response to the fuel pressure, a compression spring 21 bfor adjusting the displacement amount of the diaphragm portion 21 a, ashaft 21 c for guiding the movement of the diaphragm 21 a in apredetermined direction and a bearing 21 d for holding and making theshaft 21 c slidable.

The current control portion 22 comprises a transistor 22 a forcontrolling the current flowing through the fuel pump 4, fixed resistor22 b for protecting the transistor 22 a against an overvoltage, a fixedresistor 22 c for protecting the transistor 22 a against an overcurrent,a brush secured to the shaft 21 c and moves on a resistor surface of avariable resistor 22 d, a diode 22 f for absorbing the surge voltagegenerated at the fuel pump 4, a current control terminal 22 g, a controlinput terminal 22 h and a negative side terminal 22 i.

The brush 22 e is made of a phosphorous bronze plate for example whichhas an elasticity and a good electric conductivity, the shaft 21 c ismade of a stainless steel rod for example which has a slidability and anabrasion resistance and a good electric conductivity, the bearing 21 dis made of a copper alloy for example which has a slidability and anabrasion resistance and a good electric conductivity, and the brush 22e, the shaft 21 c, the bearing 21 d and the variable resistor 22 d areall electrically connected together.

FIG. 3 is a connection diagram for a vehicle of the fuel supplyingapparatus of one embodiment of the present invention, in which 40 is abattery, 41 a key switch and 42 is an electronic control unit forelectrically controlling the injector of the engine and for controllingan electric source relay 43 for switching on and off the electric sourceof the fuel pump 4. The output voltage from the electric source relay 43is applied through the fuel pump 4 to the current control terminal 22 gof the fuel pressure regulator 20 and to the control input terminal 22 hof the fuel pressure regulator 20. The negative terminal of the battery40 is not only grounded to the vehicle but also connected to thenegative terminal 22 i of the fuel pressure regulator 20.

The operation of the fuel supplying apparatus 100 thus constructed willnow be described in conjunction with FIGS. 1 to 3.

When the key switch 41 is turned on, a voltage from the battery 40 isapplied to the electronic control unit 42, the electric source 43controlled by the electronic control unit 42 is turned on to supply anelectric current to the control input terminal 22 h of the fuel pressureregulator 20 and the fuel pump 4. When the voltage is applied to thecontrol input terminal 22 h, a base current flows to the transistor 22through the fixed resistor 22 c and a collector current proportional tothe base current is supplied to the fuel pump 4 to drive the fuel pump4.

When the fuel pump 4 is driven, the fuel within the fuel tank 2 issuctioned through the strainer 14 and discharged from the discharge pipe11 to flow through the passage 15 in the direction of the arrow A, toreach to the lower space 16 under the filter element 5 b after passingthrough the filter element 5 b, thereafter the fuel is supplied to theinjector of the fuel injection apparatus mounted to the unillustratedengine through the pipe 12 in the direction of the arrow B and throughthe discharge pipe 7.

In this fuel pumping process, when the diaphragm portion 21 a of thefuel pressure detector portion 21 of the fuel pressure regulator 20disposed in the fuel pipe receives the fuel pressure, the shaft 21 cmoves up and downwardly to cause the brush 22 e secured to the shaft 21c to slide on the surface of the movable resistor 22 d, whereby theresistance of the variable resistor 22 d varies to control the basecurrent flowing through the transistor 22 a.

During the engine starting up, the fuel pressure within the fuel pipeconnected from the pipe 12 to the injector through the discharge pipe 7is low, so that the shaft 21 c of the diaphragm portion 21 a of the fueldetector portion 21 is positioned at a low position due to thecompression spring 21 b to cause the variable resistor 22 d to exhibit asmall resistance to allow a large base current to flow into thetransistor 22 a.

As a result, the current flowing through the fuel pump 4 increases, sothat the unillustrated motor of the fuel pump 4 is operated at fullpower to increase the fuel pressure within the fuel pipe. When the fuelpressure is increased, the shaft 21 c of the diaphragm portion 21 a ismoved upwardly (FIG. 3, in F direction) against the compression spring21 b, the resistance of the variable resistor 22 d increases, thereby tomake the base current flowing through the transistor 22 a small todecrease the current flowing through the motor of the fuel pump 4.

In this manner, due to the functions of the current control unit 22 andthe fuel pressure detection unit 21 housed within the fuel pressureregulator 20, the current flowing through the fuel pump 4 is made largewhen the fuel pressure within the fuel pipe is low and the currentflowing through the fuel pump 4 is made small when the fuel pressurewithin the fuel pipe is high, whereby the fuel pressure within the fuelpipe supplied to the injector through the discharge pipe 7 is maintainedat a prescribed value by analogue control of the current through thefuel pump 4 by a transistor 22 a.

While it is proposed, as a method for maintaining the fuel pressurewithin the fuel pipe for supplying to the injector at a prescribedvalue, that a semiconductor pressure sensor is used to detect the fuelpressure based on which a field effect transistor is digital-controlledto control the current flowing through the fuel pump 4, when the digitalturning on and off is carried out, because the motor of the fuel pump 4is the induction-type load, a reverse voltage at a high voltage isgenerated across the fuel pump 4 and an electrical noise is generated.

Contrary to this, according to the present invention, the currentflowing through the fuel pump 4 is controlled by the analogue control,the above problem does not generate.

Also, the fuel pressure, which is set by the specifications of theengine, the injector, the electronic control unit 42 and the like, canbe set by suitably selecting the strength of the compression spring 21,the resistance of the variable resistor 22 d, the resistance of thefixed resistor 22 c and the current amplification factor of thetransistor 22 a housed within the fuel pressure regulator 20. It iseffective to mount the fuel pressure regulator 20 as a unit after it isadjusted to have a prescribed value by a test device.

While the fuel pressure regulator 20 is described as being disposed onthe upper surface of the cover 3 in the forgoing description, it may bedisposed on the holder member 5 a of the fuel filter 5, and the fuelfilter 5 which has been housing within the holder member 5 a may beinserted into the fuel pipe exterior of the fuel tank 2.

Another embodiment of the present invention will now be described.

FIG. 4 is a sectional side view of the fuel pressure regulator ofanother embodiment of the present invention. In the figure, 200 is afuel pressure regulator which has a suction portion 30 having a suctionport 30 a into which the fuel discharged from the fuel pump 4 flowssecured to the lower portion of the case 23 of the fuel pressureregulator 22.

The fuel pressure regulator 200 is disposed within the fuel tank 2,outer surface portion of the fuel tank 2 or around the fuel pipe betweenthe discharge pipe 7 a and the injectors, and the fuel pipe and thesuction port 30 a are connected by the rubber hose or the like to detectthe fuel pressure suctioned within the suction port 30 a, whereby thefuel pressure suctioned in the suction port 30 a is detected andanalogue control the current flowing through the fuel pump 4 by theoperation similar to that of the fuel supplying apparatus of the firstembodiment, enabling the fuel pressure within the fuel pipe to bemaintained at a prescribed value.

In the fuel supplying apparatus having the above-described construction,the fuel pump is operated to pump the fuel amount corresponding to thatrequested by the injector mounted to the engine, so that the currentconsumption of the fuel pump is reduced and the operating noise islowered.

Also, the signal detected at the fuel pressure detection unit isinputted into the current control unit, enabling the current flowinginto the fuel pump to be accurately controlled. Also, the fuel pressuredetection unit comprises a diaphragm portion displaceable in response tothe fuel pressure, the shaft and the axis, so that the fuel pressure canbe detected by a simple structure.

Also, the current control unit comprises the transistor, the fixedresistor, the brush, the diode and the input terminal and allows thecurrent flowing through the fuel pump to be accurately controlled by theanalogue control.

Further, the fuel pressure regulator may be mounted to another positionother than the fuel supplying apparatus, the layout design is easy.

INDUSTRIAL APPLICABILITY

The fuel supplying apparatus of the present invention comprises a coverportion installed to an opening portion of a fuel tank and having anoutlet pipe disposed thereon, a fuel pump for pumping fuel within thefuel tank to an injector of an engine through the outlet pipe, a fuelfilter for filtering the fuel discharged from the fuel pump, and a fuelpressure regulator for detecting the pressure of the fuel dischargedfrom the fuel pump and regulating the discharge pressure of the fueldischarged from the pump according to the detected fuel pressure, sothat the fuel pump is set to pump an amount of the fuel corresponding tothat required by the injector mounted to the engine, whereby the currentconsumption of the fuel pump is reduced and the operating noise islowered. Also, the motor of the fuel pump is rotated at a low speed whenthe engine noise is low such as during the idling, the operating noisecan be low in order not to give an uncomfortable feeling to thepassenger of the vehicle.

Further, the fuel pressure regulating apparatus of the present inventiondetects the fuel pressure to analogue control the motor current of thefuel pump for generating the fuel pressure, which is also applicable toa combination of the pressure of a medium other than the fuel and anelectrical device for generating the pressure of the medium.

What is claimed is:
 1. A fuel supply apparatus comprising: a coverportion installed on an opening portion of a fuel tank and having anoutlet pipe disposed thereon; a fuel pump for pumping fuel within saidfuel tank to an injector of an engine through said outlet pipe; a fuelfilter for filtering the fuel discharged from said fuel pump; and a fuelpressure regulator for detecting the pressure of the fuel dischargedfrom said fuel pump and regulating the discharge pressure of the fueldischarged from said pump according to the detected fuel pressure;wherein said fuel pressure regulator comprises a fuel pressure detectionportion, and a control current portion for providing analogue control ofthe amplitude of the current flowing through said fuel pump according toa signal from said fuel pressure detection portion.
 2. A fuel supplyingapparatus as claimed in claim 1, wherein said fuel pressure regulatorcomprises a diaphragm portion displaceable in response to the fuelpressure, a compression spring for adjusting the displacement amount ofsaid diaphragm portion and a shaft for guiding the movement of saiddiaphragm in a predetermined direction.
 3. A fuel supply apparatus asclaimed in claim 1, wherein said current control portion is composed ofan analogue circuit comprising a variable resistor whose resistancevaries according to the amount of displacement of a shaft, and atransistor whose base current is controlled according to said variableresistor.
 4. A fuel pressure regulating apparatus comprising: a suctionportion for suctioning fuel; a fuel pressure detection portion fordetecting fuel pressure; and a current control portion for providinganalogue control of the amplitude of a current flowing through a fuelpump according to a signal from said fuel pressure detection portion. 5.A fuel supply apparatus comprising: a cover portion installed on anopening portion of a fuel tank and having an outlet pipe disposedthereon; a fuel pump for pumping fuel within said fuel tank to aninjector of an engine through said outlet pipe; a fuel filter forfiltering the fuel discharged from said fuel pump; and a fuel pressureregulator for detecting the pressure of the fuel discharged from saidfuel pump and regulating the discharge pressure of the fuel dischargedfrom said pump according to the detected fuel pressure; wherein saidfuel pressure regulator comprises a fuel pressure detection portion, anda control current portion for controlling the current flowing throughsaid fuel pump according to a signal from said fuel pressure detectionportion. wherein said fuel pressure regulator comprises a diaphragmportion displaceable in response to the fuel pressure, a compressionspring for adjusting the displacement amount of said diaphragm portionand a shaft for guiding the movement of said diaphragm in apredetermined direction.
 6. A fuel supplying apparatus according toclaim 4, wherein said fuel pressure regulator comprises a diaphragmportion displaceable in response to the fuel pressure, a compressionspring for adjusting the displacement amount of said diaphragm portionand a shaft for guiding the movement of said diaphragm in apredetermined direction.
 7. A fuel supply apparatus as claimed in claim4, further comprising a shaft, wherein said current control portionincludes an analogue circuit comprising a variable resistor whoseresistance varies according to the amount of displacement of the shaft,and a transistor whose base current is controlled according to saidvariable resistor.